Method of making a floor tile with elastomer  jacketed support members

ABSTRACT

A modular plastic floor tile is formed by molding a body of a first polymer compound and overmolding features onto the body from a second polymer compound. The compounds may be different from each other in hardness and/or color. The overmolded features may include skins on the sides and bottoms of support member cores disposed below the tile lower surface.

RELATED APPLICATIONS

This application is a continuation in part of copending U.S. patentapplication Ser. No. 12/609,959 filed Oct. 30, 2009, and is a furthercontinuation in part of copending International Patent Application No.PCT/US10/54515 filed Oct. 28, 2010, which in turn is a continuation inpart of pending U.S. patent application Ser. No. 12/609,959 filed Oct.30, 2009. The present application is further a division of pending U.S.patent application Ser. No. 13/217,556 filed Aug. 25, 2011. All of theforegoing applications are owned by a common assignee. Thespecifications and drawings of each of them are fully incorporated byreference herein.

BACKGROUND OF THE INVENTION

Conventional modular injection-molded tiles are known in the art forlaying across upper surfaces of garage floors, sports surfaces, outdoorsurfaces and other substrates. These tiles typically are twelve tothirteen inches square and can be manually assembled and disassembled. Acommon feature of these tiles is their ability to be snapped together,with few or no tools, using male and female connectors molded into eachtile for the purpose.

Conventional single tiles are molded to be a single, uniform color suchas all-black or all-red. The consumer typically can choose differenttiles in different colors. The consumer or contractor will often choosetwo or more colors for a particular floor, for assembly into anaesthetically pleasing pattern. But manufacturing an injection-moldedplastic tile that has two or more perceptible colors per tile is moredifficult and to date no such tile has been provided that has proven tobe acceptable to the consumer.

Many conventional modular plastic tiles are easily dislodged from theirpositions on the floor (particularly where wheeled vehicles are drivenonto and off of them) and require a rubber sheet or the like as asubstrate. It would therefore be advantageous to furnish a floor tile,for applications in which a large displacing lateral force may beapplied to the tile, and which does not require a nonslip sheet as asubstrate.

Previous attempts have been made to produce plastic modular tiles thathave cushioning characteristics. U.S. Patent Application Publication No.US 2009/0031658 A1 discloses modular athletic floor tiles that have aplurality of premolded rubber inserts which, after molding, arephysically inserted into receiving holes in a molded plastic substrate.In one embodiment each rubber insert has a face that is stands up fromthe surrounding top floor surface. The body of each rubber insertextends all the way through the plastic substrate or base and well belowits bottom. The rubber inserts are selectively compressed when anathlete stands on them, giving a cushioning effect. But it is believedthat the separate molding of these inserts, flash removal from them andphysical insertion of them into respective receiving holes in theplastic tile substrate is time-consumptive and greatly increases thecost of manufacture of the resultant tile.

A need therefore persists in the industry for modular plastic tileswhich can sustain heavy loads but have non-slip characteristics, whichwill be effectively joined together, which can be provided in aplurality of colors per tile, and which can be manufactured quickly andinexpensively.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a modular floor tile isprovided which may be used to create a flooring surface including aplurality of like tiles. A first polymer compound is used to mold a bodyof the tile. The body has at least one feature overmolded onto the uppersurface of the body from a second polymer compound which is differentfrom the first polymer compound. A second polymer compound gate isdisposed to be adjacent a lower surface of the tile body and to beremote from the upper surface thereof. The gate communicates to theupper feature through a through-hole which extends from the lowersurface to the upper surface. A vent hole, laterally spaced from thethrough-hole, extends from the upper surface back to the lower surfaceand is in communication with the upper feature. During the injection ofthe second polymer compound, molten polymer makes its way from the gate,through the through hole and into the cavity in which the upper featurewill be created. The vent hole permits gas or other fluid to bedisplaced out of the upper feature cavity, thereby obviating orminimizing any void in the as-molded upper feature which might otherwiseoccur. In one embodiment a portion of the upper pad extends through thevent hole to be disposed below or protrude onto the lower surface.Preferably, the tile has many such pads on its upper surface, and manysuch support members downwardly depending from its lower surface. Groupsof these pads and support member portions may be molded together in acontinuous phase of the second polymer compound.

The second polymer compound may differ from the first polymer compoundin rigidity, coefficient of friction, color, or some or all of these,and in one embodiment the upper feature constitutes a nonslip pad. Inone embodiment a spaced-apart plurality of such upper features areformed as connected to one gate, through a plurality of through-holes,with at least one vent hole accorded to each of the upper features. Inone embodiment the vent hole is laterally positioned to be maximallyspaced from the through hole and still be within the periphery of theupper feature. In one embodiment the periphery of the upper feature isdefined by a smoothly finished crush ring which prevents flash of thesecond polymer compound.

In another aspect of the invention, a modular floor tile of the aboveconstruction further has at least one lower feature overmolded onto thelower surface of the tile body from the second polymer compound. Thegate communicates directly with this lower feature by a path which doesnot pass through the body. The lower feature may, for example, be a“skin” overmolded over a support member core, the skin and coreconstituting a support member. A portion of the second polymer compoundmay extend from the upper feature, through the vent hole and onto thelower surface of the body, and in such embodiment it is preferred thatthe lower feature as-molded be spaced from such portion. This may beaccomplished by forming a crush pad completely laterally around suchportion and also around the lower feature. The skin may extend up atleast one sidewall of the core.

There may be a plurality of such lower features, all connected to asingle gate. In one embodiment, groups of upper features and associatedlower features all connect to respective fill points or gates, with thetile having a plurality of these groups.

In a further aspect of the invention, a method of forming a plasticmodular floor tile includes molding a body of a first thermoplasticpolymer compound, and then overmolding the body using a second polymercompound that has different characteristics from the first, such asdifferences in rigidity, coefficient of friction and/or color. The stepof overmolding includes the substeps of positioning a gate adjacent thelower surface of the tile body and remote from an upper surface thereof;flowing polymer from the gate through a vent-hole to form an upperfeature on the upper surface; and displacing a fluid (such as a gas) outof the volume of the upper feature cavity through a vent hole extendingfrom the upper surface to the lower surface thereof, thereby minimizingor obviating any void which might otherwise appear in the upper featureas molded.

In one embodiment, the method further includes flowing the molten secondpolymer compound from the gate, by a path which does not pass throughthe tile body, to a lower feature which is overmolded on the lowersurface of the body. The method may also include the step of flowingmolten second polymer compound through the vent hole such that a portionthereof protrudes onto the lower surface of the tile body. In this lastinstance the method further preferably includes spacing such portionfrom the lower feature as by a crush pad, so that the flow of polymercreating the lower feature won't conflict with the flow of polymercreating the upper feature, and so that any gas or fluid will bepositively displaced from the upper surface through the vent hole. Inone embodiment, groups of upper and lower features are each formed frompolymer flowing from a single respective gate or fill point. The methodmay be used to overmold nonslip pads on the tile upper surface and, inone embodiment, to simultaneously overmold support member nonslip skinson the lower surface of the tile.

In one embodiment, the method includes molding from a first, relativelyrigid polymer, a body of the tile and a plurality of spaced-apart groupsof support member cores, then overmolding onto the bottom surface and atleast a portion of the side of each core, a skin from a second,relatively nonrigid polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further aspects of the invention and their advantages can bediscerned in the following detailed description, in which likecharacters denote like parts and in which:

FIG. 1 is an isometric view of four modular floor tiles according to theinvention, as assembled into a portion of a flooring surface;

FIG. 2 is a front isometric view of one of the modular floor tiles shownin FIG. 1;

FIG. 3 is a back view of the modular floor tile shown in FIG. 2;

FIG. 4 is an isometric detail of the back of the floor tile shown inFIG. 3, illustrating a tile body prior to overmolding with a secondpolymer compound;

FIG. 5 is an isometric detail of the same tile region shown in FIG. 4,shown after overmolding has been completed;

FIG. 6 is a detail of the upper surface of a tile according to theinvention prior to overmolding, showing flow-through points and crushrings;

FIG. 7 is a detail of the same region illustrated in FIG. 6, shown aftertop surface pads have been overmolded;

FIG. 8 is a magnified sectional detail of two adjoining tiles showinginternal structure of the support members;

FIG. 9 is a magnified sectional detail of a tile showing therelationship of the overmolded features on the tile's lower and uppersurfaces;

FIG. 10 is magnified bottom view detail of a tile according to theinvention;

FIG. 11 is a magnified sectional view of two tiles being assembledtogether;

FIG. 12 is a magnified sectional view of two joined tiles taken throughcooperating loop and latch structure;

FIG. 13 is a diagram showing nonlinear interference between a latch anda loop according to the invention;

FIG. 14 is a schematic flow diagram illustrating steps in amanufacturing process according to the invention;

FIG. 15 is an isometric magnified detail view of a corner of a tile bodyaccording to a second embodiment of the invention, prior to overmoldinga peripheral seal thereon;

FIG. 16 is the tile body corner seen in FIG. 15, after overmolding;

FIG. 17 is a magnified sectional detail through a lateral edge of thetile illustrated in FIG. 16;

FIG. 18 is a magnified sectional detail showing joined lateral edges ofadjacent tile, taken through two cooperating peripheral seals;

FIG. 19 is a schematic isometric view of a tile according to a thirdembodiment of the invention, wherein a second polymer compound isinjected into a gate on an upper surface of the tile;

FIG. 20 is a top isometric view of a modular floor tile according to afourth embodiment of the invention;

FIG. 21 is a magnified sectional view of two tiles according to a fifthembodiment of the invention;

FIG. 22 is a magnified sectional view of the two tiles shown in FIG. 21,taken through cooperating latch and loop structure; and

FIG. 23 is a back view of a modular floor tile according to anotherembodiment;

FIG. 24 is an isometric detail of the back of the floor tile shown inFIG. 23, illustrating the tile body prior to overmolding with a secondpolymer compound;

FIG. 25 is an isometric detail of the same tile region shown in FIG. 24,shown after overmolding has been completed;

FIG. 26 is a detail of the upper surface of the tile shown in FIG. 23prior to overmolding, showing through-holes, vent holes, and crushrings;

FIG. 27 is a magnified sectional detail of the tile shown in FIG. 23,showing the relationship of the overmolded features on the tile's upperand lower surfaces; and

FIG. 28 is a schematic flow diagram illustrating steps in an alternativemanufacturing process according to the invention.

DETAILED DESCRIPTION

Modular floor tiles according to the invention can be used to form aflooring surface, a representative portion 100 of which is shown inFIG. 1. In this illustrated embodiment, the flooring surface 100 is madeup of tiles 102, including first floor tiles 102A and second floor tiles102B, which are identical except as to color. The floor tiles 102A eachhave a body 104 injection-molded from a first polymer compound,preferably comprising a polymer which is relatively rigid whensolidified and which can be selected from the group consisting ofpolyolefins including polypropylene and high molecular weightpolyethylene, rigid thermoplastic polyurethane (TPU), acrylonitrilebutadiene styrene (ABS) and rigid polyvinyl chloride (PVC). The firstpolymer compound may further include filler such as talc to aid inachieving surface flatness, and a pigment. Floor tiles 102B have bodies104 which preferably are made of a polymer compound identical to thatforming bodies 104 of tiles 102A, except possibly for the choice ofpigment or colorant. Each floor tile 102 preferably has an array offeatures 106, or raised pads, on its upper surface 108. The pads 106,which preferably are spaced apart on the upper surface 108, areovermolded onto the upper surface 108 using a second polymer compound,which has different characteristics from the first.

The differences between the first and second polymer compounds caninclude color and/or hardness. In one embodiment the second polymercompound, once solidified, is softer or less rigid than the first (oncesolidified), and has a higher coefficient of friction with respect tomost objects than does the first. In another embodiment the hardness ofthe first and second compounds (once solidified) is about the same, butthe colors are distinctly different. In a third embodiment, the hardness(once solidified) of the second compound is greater than that of thefirst. In a preferred embodiment, the second polymer compound can beselected from the group consisting of styrene ethylene butylene styrenebased thermoplastic elastomer (SEBS TPE), other TPEs, soft TPU, or softPVC. Polypropylene as the principal polymer in the first compound, andSEBS TPE as the principal polymer in the second polymer, areparticularly preferred and have demonstrated good adherence to eachother.

One aesthetic advantage of the invention is that the first and secondpolymers can be provided in contrasting colors, and that because of themolding techniques used in the invention, pads 106 can be coloreddifferently than upper surface 108 yet present a sharp, commerciallyacceptable appearance.

A top isometric view of one tile 102 is shown in FIG. 2. The body 104 oftile 102 is in main part a substantially horizontal and planar web 200that has a plurality of lateral edges 202, 204. Each of the web edges202, 204 downwardly depends from the upper surface 108 to a lowersurface (not shown in FIG. 2). In the embodiment illustrated in FIG. 2,edges 202, 204 are orthogonal to surface 108, are planar and are atright angles to each other. But the tile 102, and the edges 202, 204 ofit, can take other shapes. For example, the tile 102 can be hexagonal ortriangular, and the edges 202, 204 could be wavy or curved instead ofstraight. Instead of edges 202, 204 being planar, as shown, they couldbe stepped or have tongues and corresponding grooves (see FIGS. 15-16for an embodiment in which the lateral edges are stepped). It ispreferred, however, that the shape and profile of each web edge 202 becomplementary to the shape and profile of each web edge 204, such thatwhen adjacent tiles are joined together, edges 202 and 204 will fittogether closely.

The illustrated embodiment has a two-dimensional array of sixty-fourraised pads 106 as located on a square surface of about twelve inches inlength and width. Alternatively there could be as few as one pad 106,which preferably would be larger and possibly elongated and branchedand/or sinuous. It is preferred to have a regular pattern of the pads106 so that sub-units of the tile 102 can be trimmed off of it, in amanner to be explained below, and so that as trimmed the tile 102 willretain an aesthetically pleasing appearance. The illustrated pads 106are rounded squares but could take other shapes such as circles, ovals,hexagons, triangles, distinctive logos or other shapes.

The first edges 202 each are equipped with at least one, and preferablyseveral, latches 206. The second edges 204 each have at least one, andpreferably several, loops 208. It is preferred that the number oflatches 206, distributed in spaced relation along first edge 202, equalthe number and position of loops 208, which are distributed in likespaced relation along each second edge 204. In the illustratedembodiment the latches 206 are pressed downward and snapped into loops208, in a manner which will be described in further detail below.

In the bottom view of tile 102 shown in FIG. 3, there can be seensixteen groups 300 of support members 302. According to one aspect ofthe invention, each support member 302 is formed in part by a skin 304of a relatively soft polymer compound such as once comprising TPE, andhas a core that is molded as part of the body 104 from apolypropylene-based compound or other relatively rigid polymercomposition. Some of the support members 302 are annular and take theshape of squares with empty centers. Other support members 302 in eachgroup 300 are short linear segments. The support members will bediscussed in further detail below. Preferably the general lower surface306 also has, depending downwardly from it, a plurality of elongaterigid support ribs 308 that have no TPE or other soft polymer skin. Thesupport ribs are integrally molded with the web 200 of body 104.

In the illustrated embodiment, the rigid support ribs 308 form partialoutlines of rounded squares, each one of which contains one of thegroups 300 of the support members 302. The rigid support ribs 308 are sopositioned that one or more of them are not very far away from any group300 of support members 302. This permits the rigid support ribs 308 toaccept most of the load of heavy objects (such as vehicles) imposed onthe upper surface 108 of tile 102.

The elongate ribs 308 also define and delimit linear channels 310, oneset of which are aligned along a length of the tile 102, and another setof which are at right angles to these and are aligned along a width ofthe tile 102. The channels 310 are disposed between, rather thanthrough, the support member groups 300 and (on the upper surface) thepads 106. This provides the consumer a trim guide for cutting apart tile102 in a lengthwise or widthwise direction, or both, in predeterminedincrements such as three inches or twenty-five percent of tile 102'slength or width. As projected onto the single horizontal plane occupiedby web 200, the center line of each channel 310 will substantiallyexactly bisect the distance between the centers of adjacent pads 106 oneither side of the center line. The distance from the center line of thechannel 310 to a center of a pad 106 is one-half of the distance fromone center of a pad 106 to a next adjacent pad 106. Since pads 106,support member groups 300, latches 206 and loops 208 repeat in a regularpattern, such as on three-inch centers, and since the pads 106 areexactly twice as far apart from each other as the closest of them are tothe edge 202 and/or 204 (see FIG. 2) or a channel 310, the consumer mayuse trimmed tiles on the periphery of the flooring surface to extend theflooring surface by another three, six or nine inches, or alternatively25%, 50%, or 75% of the length or width of tile 102. The regular patternand spacing of raised pads 106 will continue over from untrimmed tilesonto such trimmed peripheral tiles without visually noticeableinterruption and therefore the result will be aesthetically pleasing.

FIGS. 4 and 5 are details of the tile lower surface, showing a singlegroup 300 of support members 302 before and after a second polymercompound is overmolded onto the body 104 of the tile 102. In FIG. 4there can be seen a plurality of support member cores 400 which dependdownwardly (in this view, extending toward the top of the paper) from ageneral lower surface 306 of the substantially horizontal web 200 thatmakes up most of the tile body 104. The cores 400 do not downwardlydepend as far as the support ribs 308. Ribs 308 are not overmolded. Inthe illustrated embodiment there are provided, in each group 300 ofsupport members 302, four annular cores 402 and eight cores 404 formedas short linear segments and in parallel pairs nearby the annular cores402. Also seen here is, for this group 300, a crush pad 406 which in useis slightly lower than the general surface 306 (in this bottom view, pad406 is slightly raised relative to general surface 306). The crush pad406 is formed to be closely adjacent all of the support member cores 400and laterally surrounds all of the cores 400 and the runners 502connecting the support members. The crush pad 406 is finished to have asmooth surface (general lower surface 306 can instead be textured) andis used as a shutoff surface to prevent the flashing of the secondpolymer compound during a “second shot” or overmolding step offabrication.

FIG. 5 shows the same area after overmolding. A skin 304 of the secondpolymer now appears on the bottom surfaces and sides of each of thecores 400, and in this embodiment completes the support members 302.While in one embodiment the skins 304 could be overmolded separately oneach core 400, in the illustrated embodiment the skins 304 within thesupport member group 300 are part of a continuous phase. To save cost,the area covered by skins 304 is limited and, as seen in FIGS. 3 and 5,does not include a majority of the tile body lower surface 306. Theskins 304 preferably do not extend to cover the centers of the annularcores 402 or other regions outside of crush pads 406. Lateral runners502 connect a common fill point 504 to each of the skins 304. It hasbeen found that as the second of a double-shot injection, skins 304molded of a SEBS TPE compound have excellent adherence to the preferablypolypropylene compound cores 400 (FIG. 4). As completed, the compositesupport members 302 are of approximately the same depth (in a directionorthogonal to the web 200) as the support ribs 308. The support members302 provide further structural support to the web 200 but at the sametime act as a friction surface to grip the surface upon which the tilesare laid.

FIGS. 6 and 7 are details of a similarly sized area on the top of tile102, before and after overmolding, illustrating one group of pads 106,which are interconnected in a continuous phase of solidified secondpolymer compound. In the illustrated embodiment, each of the overmoldedpads 106 resides in a shallow recess or receptacle 600 whose surface islower than that of the general upper surface 108. For each recess 600there is provided at least one through-hole 602 which communicates thetop surface of the tile web 200 to a lower surface thereof. In theillustrated embodiment the through-holes are a small fraction (about 5%)of the bottom of the recesses 600, as the viscosity (at moldingtemperature) of the preferred second polymer compound is low enough, andthe second-shot temperature and injection pressure are high enough, thatno larger through-holes are necessary to flow molten polymer from thelower side of the tile body 104 to the upper side thereof, nor is morethan one through-hole per recess 600 necessary in the preferredembodiment. Limiting the size of through-holes 602 enhances thestructural integrity of the tile 102. However, in alternativeembodiments, the size and/or number of the through-holes 602 may beincreased to accommodate more highly viscous second-shot polymercompounds.

The recesses 600 are each laterally surrounded by a crush ring 604. Eachcrush ring 604 is finished to be smooth (in contrast, the general uppersurface 108 of the body 104 is preferred to be textured) and is slightlyraised relative to the general upper surface 108. The crush rings 604provide a tight overmold shutoff that prevents the flashing of thesecond polymer compound outside the confines of the crush rings 604.

FIG. 7 is a detail of the tile upper surface after the overmolding step.The second polymer compound is injected into the mold at one or morepoints adjacent the lower surface of body 104, flows through each of thethrough-holes 602, and occupies cavities in the second-shot mold tocreate the raised pads 106. A top surface of the pads 106 is raisedabove that of general surface 108, creating a nonslip surfacecharacteristic. Through this methodology overmolding artifacts on theupper surface of the tile 102 are avoided, producing a more pleasingappearance.

FIG. 8 is a sectional view of two tiles 102 joined together, takenthrough annular support members 800, linear support members 802 andrigid ribs 308. Each skin 304 completing a support member 800, 802 has aportion 810 which is formed on the lower end or bottom surface of eachcore 400, 402. Preferably, each skin 304 also includes portions 812which cover all or portions of adjoining side walls of the cores 400,402.

The rounded square or annular support members 800 are each inapproximate registration or alignment with the edges or lateralperiphery of a respective raised pad 106 on the upper surface 108 of thetile 102. The support members 800 will receive any weight placedparticularly on the raised pads 106 and will prevent any shear stressfrom developing in nearby regions of the horizontal web 200. The supportmembers 800 and 802 each help support weight placed on the upper surface108 of tile 102, while at the same time providing a friction or nonslipsurface that will engage the substrate on which the tile is placed. Therigid members 308 provide rigid support of the entire tile 102 anddelimit any compression of the TPE skin 500, the lower surface of whichis preferably in the same plane as the lowest portion of ribs 308. FIG.8 also shows the preferred profile of lateral edges 202, 204, which isplanar and orthogonal to the plane of web 200. The components of theadjacent tiles 102 in FIGS. 8 and 9 have been stippled differently toillustrate that they can be of different colors.

FIG. 9 is a magnified diagonal cross section (lower side up) of part ofa tile 102, taken through two raised pads 106, support members 800underneath and in approximate registry with respective ones of theraised pads 106, a central fill point 504 and two runners 502. In thisillustrated embodiment, one central second-shot polymer compound fillpoint 504 is provided for the skins of an entire group 300 of twelvesupport members 800, 802, and four associated raised pads 106 on theupper surface 108 of the tile 102. This illustrated embodiment hassixteen fill points 504 on tile 102, one for each interconnected group300 of support members 302 and associated pads 106. In an alternativeembodiment the polymer compounds used for different ones of the fillpoints could be in different colors, producing groups of pads 106 on theupper surface 108 which are colored differently than other groups ofpads 106.

The central fill point 504 is connected by a set of runners 502 whichextend laterally from the fill point 504, and on the lower surface ofthe web 200, to each of the support members 800, 802 in the group 300where the fill point 504 is located. In the illustrated embodiment,there are four main runners 502 that are separated by ninety degreesfrom each other. At its end remote from the fill point 504, each runner502 branches into three branches 900 that respectively connect to anannular support member 800 and two flanking linear support members 802.As can be seen in the sectioned runners 502, one of the branches 900 ofeach runner 502 is continuous with a through-hole 602, providing aconduit for the second polymer compound to the upper side 108 of thetile 102.

FIG. 9 also shows a latch 206 which has been inserted into a respectiveloop 208. The loop 208 is preferably molded as an extension of a rigidrib 308 in an adjacent tile 102. The latch 206 is integrally formed withweb 200 and is formed in a gap between two ribs 308 that are adjacent anedge 202. The gap forming the discontinuity in linearly aligned ribsegments 308 is large enough to have the latch 206 and the loop 208disposed therebetween.

FIG. 10 is a bottom plan view of a one-sixteenth portion 998 of a tile102, the illustrated portion 998 occupying an outer corner of tile 102.This corner 998 has three ribs 308 that surround the group 300 ofsupport members 302. A rib segment 1000 is aligned with and positionedslightly laterally inwardly from an edge 204 of the tile 102. Ribsegment 1000 continuously curves on its left side (as seen in thisFIGURE) to form a boundary for a channel 1002. Rib segment 1000 has asection 1004 which continuously curves from the right side of ribsection 1022 to become parallel and laterally inwardly offset fromlateral edge 202, terminating at a gap 1006. A rib segment 1008 definesan upper right hand boundary of the portion or cell 998 and includes aportion 1010 that is in parallel with the lateral edge 202, a portion1012 which helps define a boundary for a trim channel 1014, and a curvedportion in between these. A third rib segment 1016, defining an interiorcorner of the cell 998, includes a portion 1018 that helps definechannel 1002, a portion 1020 that helps define channel 1014, and acurved transition between them.

A portion 1022 of the rib segment 1000 that is near and parallel tolateral edge 204 has a loop 208 integrally formed with it. The loop 208is connected to the rest of tile 102 only by a pair of widelyspaced-apart and limited connection points 1024 and 1026. Across-section of loop 208 and its length between connection points 1024and 1026 are so preselected that loop 208 will be relatively flexible incomparison to the latch 206. The latch 206 may be a solid plug (notshown) or, as appears in the illustrated embodiment, may include adownwardly depending, inwardly facing convex wall 1028, connected atboth of its ends to a downwardly depending, laterally outwardly facingwall 1030. The entire wall 1028, and a substantial portion of the wall1030, are attached to the general lower surface 306 of the tile 102.Neither arcuate wall 1028 nor wall 1030 is as long as loop 208. Thesedifferences in size and degree of attachment to the rest of the tile 102make the latch 206 substantially rigid relative to loop 208. In anyinterference between them, therefore, the loop 208 will flex or expandand the latch 206 will not substantially deform.

FIG. 11 is a highly magnified sectional view showing how a male latch206 is snapped into a receiving female loop 208 of an adjacent tile 102.The outer wall 1030 of the latch 206 has a surface 1100 which is beveledor sloped so that it will cam against an upper corner 1102 of thelateral edge 204. The inner wall 1028 of the latch 206 has a sloped orbeveled surface 1104 which will cam against an upper interior corner orridge 1106 of the loop 208. As the latch 206 is pressed downward intothe loop 208, an interference will develop between the inner facing wall1028 of the latch 206 and the loop 208, as shown by the hatched region1108. Since wall 1028 of latch 206 is substantially more rigid than loop208, the loop 208 will elastically expand along its length and will flexlaterally outwardly from the tile 102 to which it is attached (in FIG.11, rightward). Once the latch 206 is driven down far enough, ahorizontal ledge 1110 of the outer latch wall 1030 will snap past alower corner 1112 of the lateral edge 204 and will slide to the leftalong the general lower surface 306 of the adjacent tile 102. Even afterthis happens the loop 208 will remain under tension. This biases lateraledge 204 against mating lateral edge 202, producing a tight fit of thesetwo surfaces and the tiles of which they are a part. As shown, the depth(in a direction orthogonal to the plane of web 200) of walls 1028, 1030is slightly less than the depth of the walls of rib segment 1022 andloop 208, permitting a degree of overdrive when snapping the latch 206into the loop 208. FIG. 12 is an isometric sectional view of twoadjacent tiles taken through a loop 208 and an inserted latch 206, againillustrating the interference fit between the two.

FIG. 13 is a schematic detail, from a bottom view, showing a latch 206as it is received into a loop 208. The loop 208 is illustrated here inits unstretched and unflexed condition. As so superimposed a region 1108of interference will exist between loop 208 and an inner wall 1028 ofthe latch 206, and this region 1108 will be of variable depth asmeasured in a lateral inward/outward direction. The inner wall 1028 hasan inwardly-facing surface 1300 which has on it a point 1302 which isinnermost and is farthest away from the lateral edge 202 of body 104(see FIGS. 11 and 12) with which it is most closely associated.Preferably the inwardly-facing surface 1300 is arcuate and convexly sorelative to the center of the tile 102. Surface 1300 can be more sharplycurved than is shown. As one travels away from the innermost point 1302along the surface 1300 (to the left or right in this FIGURE), the depthof interference region 1108 decreases, until the interference region1108 vanishes altogether as one approaches either end 1304, 1306 of thesurface 1300. Preferably the inner surface 1308 of the loop 208 isarcuately concave. More preferably the degree of concavity of the innersurface 1308 is less than the degree of convexity of the inward facingsurface 1300 of the latch 206, that is, the surface 1308 is moregradually curved than surface 1300. In this way, the interference isminimized at the attachment points 1024, 1026, preventing the loop 208from becoming over-stressed at its attachment points 1024, 1026 andreducing the likelihood of loop failure. It is relatively easy for loop208 to stretch and flex at its middle, opposite innermost latch wallpoint 1302, as the length to either point 1026 or point 1024 is long.But the resistance to such stretching and flexing will increase as oneapproaches point 1024 or point 1026, as the points of attachment arecloser. Varying the degree of interference in the manner shown thereforereduces the stress at the attachment points 1024, 1026. The attachmentpoints 1024, 1026 may be reinforced with gussets 2502 (see FIG. 25) toprevent loop breakage.

FIG. 14 is a schematic block diagram illustrating steps in a floor tilemanufacturing process according to the invention. Step 1400 is a molddesign step including many substeps, of which three are pertinent here.The mold (and the part produced thereby) should have certaincharacteristics, and these include the provision of flow-through holesat substep 1402. The flow-through holes are positioned to communicatethe recesses 600 for the pads 106 (see FIG. 6), on the upper surface108, to the central second polymer compound fill points 504 adjacent thelower surface 306. The second shot of polymer compound will use theseflow-through holes (602 in FIG. 9) to access the cavities 600 in whichthe pads 106 are to be created. The size and number of through-holes 602will be dictated in part by the viscosity of the second polymer compoundat molding temperature, and the injection molding pressure to be used.

The designer also, at substep 1404, provides for crush rings 604 (FIG.6) on the top surface 108 of the tile 102, and crush pads 406 (FIG. 8)on the bottom surface 306 of the tile 102. These surfaces preferably areflat, smooth, and slightly raised or outward in relation to the rest ofthe surfaces of which they are a part. The crush rings 604 and crushpads 406 closely laterally surround the regions into which the secondpolymer compound is to flow, creating a clean shutoff of the secondpolymer compound and preventing flashing. This is particularly importanton the upper surface 108 as it will affect the aesthetic acceptabilityof the tile 102.

At substep 1406, the designer provides runners 502 (see FIG. 9) tocommunicate the central fill points 504 with the support members 800,802 and the through-holes 602. The result of step 1400 will be toolingthat can be used in a two-shot injection molding process according tothe invention.

The mold is placed in an injection molding press and a first shot ofpolymer compound is injected into the mold at step 1408. As explainedabove, this first polymer compound is thermoplastic and preferably isrelatively rigid, and can comprise polypropylene. Then, at step 1410,the mold is prepared for a second injection shot, in which furthermolding structure is used to define surfaces of pads 106, skins 304 andrunners 502. A second shot of polymer compound is then injected into themold, using a second polymer compound which has differentcharacteristics than the first polymer compound, such as being harder orsofter or being of a different color. Preferably the second polymer iselastomeric and for example can be constituted by SEBS TPE or anotherTPE. A preferred result of molding steps 1408 and 1410 is a compositefloor tile which includes a body capable of withstanding a large amountof weight (such as might be imposed by a vehicle wheel) but still hasnonslip characteristics on both its upper and lower surfaces.

FIGS. 15-18 illustrate an embodiment of the invention in which theovermolded structure includes a peripheral seal that is used to seal toadjoining tiles when a floor surface is assembled. FIG. 15 is anisometric view of a floor tile body 1500 that is similar to body 104(FIG. 2) but with lateral edges 1502, 1504 that are stepped rather thanorthogonal to the web 200 and planar. This view is taken after moldingthe first polymer compound but prior to overmolding. In this illustratedembodiment, stepped lateral edge 1502 has a laterally inwardly disposedvertical surface 1506 which extends downwardly from general uppersurface 108 to a horizontal shelf 1508. The horizontal shelf extendslaterally outwardly from vertical surface 1506 to a second, laterallyoutwardly disposed vertical surface 1510. Vertical surface 1510 extendsfrom the shelf 1508 to the lower surface 306 of the tile body 1500.

In the illustrated embodiment a lateral edge 1504 is similar in form tolateral edge 1502. A first, laterally inwardly disposed vertical surface1512 extends from general upper surface 108 of the tile body 1500 to ashelf 1514. The shelf 1514 extends laterally outwardly from the verticalsurface 1512 to a second, laterally outwardly disposed vertical surface1516. The vertical surface 1516 extends from the shelf 1514 to thegeneral lower surface 306 of the tile body 1500. Surfaces 1506, 1508 and1510 define a recess (more particularly, a step) 1518 which can besubsequently occupied by an overmolded peripheral seal. Similarly,surfaces 1512, 1514 and 1516 define a step 1520 which can besubsequently occupied by an overmolded peripheral seal, preferablycontinuous with the seal occupying step 1518. While this illustratedembodiment uses steps 1518, 1520 as locations which can be occupied by aperipheral seal, other profiles are possible, such as curved or keyedprofiles and/or ones which include a physical interference to thedelamination of the peripheral seal from the body 1500. As before, it ispreferred to mold the body 1500 from a relatively strong and rigidpolymer compound such as one comprising polypropylene.

FIG. 16 shows the view shown in FIG. 15, but after at least oneovermolding step in which a peripheral seal 1600 has been overmoldedinto the steps 1518, 1520 to laterally surround the body 1500. Thecreation of the seal 1600 can take place during, before, or after thecreation of the raised pads 106 and skins 304 (FIG. 9), and the seal1600 can be constituted by a polymer compound which is the same as orwhich is different from the polymer compound constituting pads 106 andskins 304, in terms of composition, hardness, and/or color. It ispreferred that the seal 1600 be constituted by a compound comprisingSEBS TPE or other elastomeric compound.

A top surface 1602 of the seal 1600 is preferred to be coplanar with thegeneral surface 108 of the body 1500. On one side of the tile body 1500,the horizontal surface 1602 extends from vertical surface 1506 laterallyoutwardly to a vertical surface 1604 of the seal. The vertical surface1604 of the seal extends from seal horizontal surface 1602 until itmeets with vertical surface 1510 of the body 1500, with which it iscoplanar. As better seen in FIG. 17, the otherwise planar verticalsurface 1604 is interrupted by a bump 1606 which is convex in section.

On an adjacent side of the body 1500, a horizontal surface 1608, whichis continuous with the surface 1602 and preferably coplanar with uppersurface 108 of body 1500, extends laterally outwardly from the lateraledge of vertical surface 1512 to a vertical surface 1610 of the seal1600. The vertical surface 1610, which in general is orthogonal tosurface 108 and planar, is interrupted by a convex bump 1612. Otherwise,surface 1610 meets and is coplanar with vertical surface 1516 of thebody 1500. Surfaces 1604, 1610 form a ninety degree corner at theirjunction.

As shown in FIG. 18, when adjacent tiles 1800 are assembled such that alatch 206 is inserted into a loop 208, the bumps 1606, 1612 are ininterference with each other, as shown by hatched interference region1614. This creates a substantially watertight peripheral seal of eachtile to the other tiles in the floor surface.

A further embodiment of the invention is shown in FIG. 19, in whichcertain structure adjacent the lower surface 306 of a tile 1900 is shownin phantom. This embodiment is similar to that shown in FIG. 2, with thedifference that the second shot of polymer compound is introduced atupper surface 108 of the body 104, rather than at lower surface 306thereof. For each of a group 300 of pads 106 and skins 304, a gate 1902is formed to extend from the upper surface 108 of body 104 to the lowersurface 306 thereof. The gate 1902 is continuous with runners 502 on thelower surface, which in turn communicate with the skins 304, thethrough-holes 602 and the cavities 600 in which are molded the pads 106.In making the second-shot injection, the second polymer compound flowsthrough the gates 1902 to the lower surface 306, thence through runners502 to the skins 304 and the through-holes 602, and finally back throughthe body 104 to the cavities 600 to mold the pads 106. In an alternativeembodiment, the pads 106 are omitted and only structure adjacent lowersurface 306 is molded, except for dots on the upper surface that resultfrom the gates 1902.

It is possible to overmold certain features on the bottom surface of thetile without creating raised pads from the second polymer compound onthe top surface thereof A top surface of such an embodiment can be seenin FIG. 20, in which the entire top surface 2000 of a tile 2002 ismolded of the first polymer compound. While the top surface 2000 can befeatureless except for texturing, in this illustrated embodiment anarray of features 2004, which can be rounded squares or which can takeany other desired shape, are upstanding from a general top surface 2006.A bottom surface of this illustrated embodiment can be exactly as itappears in FIGS. 3, 5, 10, 12 and 13. In this embodiment there are nothrough-holes or gates between the upper and lower surfaces of the tile2002. This embodiment and the embodiment shown in FIGS. 1-13 can be madeusing much the same molding apparatus, by swapping out a cavity-sidemold insert adjacent the top surface 108, 2000 and leaving a core side(adjacent the lower surface) alone. This illustrated embodiment willstill exhibit non-slip properties relative to the substrate on which itis placed, may have better chemical and wear resistance, and may costless to produce.

Considering together the embodiment illustrated by the combination ofFIGS. 3, 5, 10, 12, 13 and 20, raised features 2004 are more likely toreceive a disproportionate amount of weight from a vehicle or otherheavy object superimposed on the tile 2002. It is therefore preferredthat some of the support members, such as members 800 (FIG. 8), receiveall or some of the columnar load placed on any raised feature 2004. Inthe illustrated embodiment, each annular support member 800 (see FIG. 8)is in approximate registration with a respective raised feature 2004 andas such will militate against shearing between the boundary of theraised feature 2004 and the surrounding general surface 2006.

FIGS. 21 and 22 show a fifth embodiment of the invention in whichmodifications to the latch and loop structure have been made. In thisembodiment an undercut or trench 2100 is made behind (laterally inwardlyfrom) the lateral edge 204, but laterally outwardly from the rib segment1022, to approximately fifty percent of the thickness of web 200. Theundercut 2100 extends in parallel to edge 204 for the interior length ofthe wall segment 1022 between its attachment points (1024, 1026; FIG.10) with female loop 208. The undercut 2100 leaves a downwardlydepending flange 2102 which, when surface 2104 of outer wall 2106 slidesvertically downward along surface 204, will flex inward (to the left inthis picture) in approximately the direction of arrow 2108. The depth ofthe undercut 2100 is chosen to get a sufficient flexure of the flange2102 upon snapping the tiles together, and may be more or less deep thanshown depending on the flexural modulus of the polymer used to mold tilebody 104. Flexing flange 2102 permits latch 206 to more easily snap intoloop 208 and places less stress on loop 208 while joining two adjacenttiles. The inner latch wall 2110 may be made thicker and preferentiallyhas a preferably flattened, inner ramped surface 2112 which cams againstcorner 1106 as the right tile 102C is pressed downward to join it withleft tile 102D, until ledge 2120 clears lower edge 2116 of flange 2102.Ramped surface 2112 preferably extends downwardly and laterallyoutwardly from innermost limit 1302 of latch 2118. After the tiles 102C,D are snapped together, there will remain a hatched interference region2114 between inner latch wall 2110 and outer female loop 208, keepingthe tiles 102C, 102D biased together or in compression with each other;the physical position of loop 208 will actually be displaced rightwardfrom that shown in FIG. 21.

Preferably a lower edge 2116 of the flange 2102 is slightly relieved (orupwardly displaced) from the plane of the general lower surface 306.This permits an easier overdrive of male latch 2118 into female loop 208and better assures an audible click when horizontal ledge 2120 snapsbeyond lower edge 2116.

FIGS. 23 through 27 show another embodiment of the invention. In thisembodiment, the bottom view of a tile 2301, shown in FIG. 23, showssixteen groups 2300 of support members 2302. The body 2303 may be moldedfrom a first polymer compound and have an upper surface 2602 (see FIG.26) and a general lower surface 2306. One or more upper features 106(FIG. 2), such as pads, may be formed or overmolded into the uppersurface 2602 with a second polymer compound. As completed, the upperfeatures or pads 106 on upper surface 2602 (FIG. 26) may look identicalto the ones of embodiments previously described herein. One or morelower features 2302 (FIG. 23), such as support members or skins, may beovermolded onto the lower surface 2306 of the body 2303 from the secondpolymer compound. As above, the second polymer compound preferably has ahigher coefficient of friction than the first polymer compound so thatthe upper features 106 and the lower features 2302, or skins, act asnonslip surfaces. Alternatively or additionally, they may be made in acolor different from that of the tile body 2303.

FIGS. 24 and 25 show the details of the tile lower surface 2306.Specifically, these FIGUREs show a single group 2300 of support members2302 before (FIG. 24) and after (FIG. 25) the second polymer compound isovermolded onto the body 2303 of the tile 2301. FIG. 24 shows there canbe seen a plurality of support member cores 400 which depend downwardly(in this view, extending toward the top of the paper) from the generallower surface 2306 of the substantially horizontal web 200 that makes upmost of the tile body 2303. One or more through-holes 602 connect theupper surface 2602 (see FIG. 26) with the lower surface 2306. Similarly,one or more vent holes 2402 connect the upper surface 2602 with thelower surface 2306 of the tile 2301. Preferably, each vent hole 2402 isin a location that is laterally interior to and within a periphery of arespective upper feature 106. Each upper feature 106 has a through-hole602 and a vent hole 2402 communicating to it and these are laterallyspaced from each other. Preferably the vent hole 2402 for any particularpad 106 should be positioned at a location that is farthest from thethrough-hole 602 therefor, while still being laterally within theperiphery of the cavity that will form the pad or upper feature 106.

FIG. 26 shows the details of an area on the top of tile 2301, prior toovermolding. Each overmolded pad 106 (see FIG. 7) may reside in ashallow recess or receptacle 2600 whose surface is lower than that ofthe general upper surface 2602. For each recess 2600, there is providedat least one through-hole 602 and at least one vent hole 2402, each ofwhich communicates the top surface of the tile web 200 to a lowersurface thereof. In the illustrated embodiment, the through-holes 602and vent holes 2402 make up a small fraction (about 5% each) of thebottom of the recesses 2600. Each of the recesses 2600 form respectivelower portions of the cavities in which upper features or pads 106 willbe formed, the remainder of the surfaces thereof being constituted bythe other mold half. Limiting the size of through-holes 602 and ventholes 2402 enhances the structural integrity of the tile 2301. However,in alternative embodiments, the size and/or number of the through-holes602, and even vent holes 2402, may be increased to accommodate morehighly viscous second-shot polymer compounds.

The recesses 2600 are each laterally surrounded by a crush ring 604. SeeFIG. 26. Each crush ring 604 is finished to be smooth (in contrast, thegeneral upper surface 2602 of the body 2303 can be textured) and can beslightly raised relative to the general upper surface 2602. The crushrings 604 each adjoin the periphery of a respective upper feature 106and provide a tight overmold shutoff that prevents the flashing of thesecond polymer compound outside the confines of the crush rings 604.FIG. 25 further shows that a portion 2310 of at least one upper feature,or pad, 106 (see FIG. 7) may extend through the vent hole 2402 below thegeneral lower surface 2306. As shown in FIGS. 23 and 25, the portion2310 extending through the vent hole 2402 may be discontinuous with orspaced from the second polymer compound of the lower support member2302. As described in more detail below, this spacing may beaccomplished by providing a portion of the crush pad 2406 between thevent hole 2402 and the cores 400.

The crush pad 2406 is formed into the body 2303 in a manner similar tothe crush ring 604 to be slightly lower than the general surface 2306(in this bottom view, is slightly raised relative to general surface2306). The crush pad 2406 is formed to be closely adjacent all of thesupport member cores 400 and to laterally surround all of the cores 400,the runners 502 connecting the lower features 304, the through-holes602, and the vent holes 2402 (and therefore portions 2310). The crushpad 406 is finished to have a smooth surface and is used as a shutoffsurface that prevents the flashing of the second polymer compound duringa “second shot” or overmolding step of fabrication.

In an arrangement similar to that illustrated and described previously(see FIG. 19), a second polymer compound gate 1902 is disposed to beadjacent to the lower surface 2306 and remote from the upper surface2602. The gate 1902 communicates with the upper feature 106 through fillpoint 504 and a through-hole 602 that extends from the lower surface2306 to the upper surface 2602. The gate 1902 is in direct communicationwith each lower feature 2302 by a path which does not pass through thebody 2303.

FIG. 25 shows the same area after overmolding. The second polymercompound now appears on the bottom surfaces and sides of each of thecores 400 as a lower feature 2302 or skin. While the second polymer skincould be overmolded separately on each core 400, in the illustratedembodiment, the second polymer within the support member group 2300 ispart of a continuous phase. The second polymer preferably does notextend to regions outside of, and is contained by, the crush pads 2406.

FIG. 27 shows that a plurality of upper features 106 and lower features800, 802 can be formed from one gate 1902 (FIG. 19). It can be seen thatthe molten second polymer flows from the gate 1902 (see FIG. 19) to thefill point 504 and directly to the lower surface 2306 to form the lowerfeatures 800, 802. This path does not go through the first-shot tilebody 2303. FIG. 27 also shows that each upper feature 106 is incommunication with a respective vent hole 2402. The second polymer flowsfrom the gate 1902, to the fill point 504, and through the through-hole602 to form a respective upper feature 106. For each feature or pad 106,the second polymer flows from the through-hole 602 and flows into andfills a respective mold cavity formed in part by a recess 2600, and backthrough the vent hole 2402. In this way, any gas in the polymerflow-path is displaced, and defects or voids at the end-of-fill point inthe overmolded upper feature 106 caused by trapped gas can be minimizedor prevented. This trapped gas otherwise can cause burn marks, shortshots, and/or poor adhesion of the upper features 106 to the body 2303.

The structure shown in FIG. 24 is one possible first-shot body structurethat promotes the displacement of any gas out of the upper featurecavity. Each core 400 may be interrupted or truncated to provide lateralseparation from the vent hole 2402, which is preferably placed at aposition farthest away from the through-hole. Where, as here, the upperfeature 106 takes on a roughly square or rectangular shape, thethrough-hole 602 and the vent hole 2402 can be disposed in oppositecorners of the upper feature. The positioning of vent hole 2402preferably should be such that the molten second-shot polymer flowingfrom the through-hole 602 will reach the vent hole 2402 only afterreaching the rest of the cavity defined in part by recess 2600. Aftermolding (FIG. 25), the separation between core skin 2302 and portion2310 is maintained by the crush pad 2406, which seals the portion 2310of the upper feature 106 or pad extending through the vent hole 2402from the lower features 2302 or skins molded onto the cores 400. Thisseparation of the top flow (through the through-hole 602, over therecessed area 2600, and through the vent hole 2402) and the bottom flow(from the fill point 504, to the runner 502, to the lower feature 2302or skin) prevents the top and bottom flows from interfering with oneanother in correctly filling the volumes into which the second polymeris to be overmolded.

FIG. 28 illustrates a method 2800 of manufacturing a modular floor tile2301 according to the invention. At 2802, the first-shot injection moldis formed, including forming (2804) structures which will make one ormore through-holes 602, and forming (2806) one or more vent holes 2402.Optionally structures which will form one or more recesses 2600 can beformed at step 2808, the recesses 2600 then acting as portions of thecavities in which the upper features or pads 106 will be later molded.At step 2810, structure defining the crush ring(s) 604 are formed on theupper surface 2602 of the first-shot body 2303, so as to laterallysurround each upper feature and preferably to be elevated above thegeneral upper surface. For each such upper feature, at least onethrough-hole and at least one vent hole is made, and these preferablyare spaced to be at opposite ends of the upper features to which theycommunicate. At step 2812, crush pad(s) 2406 are defined on the lowersurface 2306 of first-shot body 2303, so as to laterally surround eachlower feature to be molded in the second shot, and also to laterallysurround each vent hole 2402.

At step 2814, the second-shot mold half is created. The structuresformed in this step include a fill point or gate 504, 1902, which islocated to be adjacent the lower surface 2306 of the first-shot body2303 and remote from the upper surface 2602 thereof. Cavities for thesecond-shot runners 502 (FIG. 27) are also formed at this step.

The first polymer compound is injected into the first-shot injectionmold at step 2820; this will form a first-shot tile body 2303 as seen inFIGS. 24 and 26.

The second polymer compound is injected into a second-shot injectionmold at step 2822, to overmold upper features 106, and preferably alsolower features 800, 802, onto the respective upper and lower surfaces ofthe tile body. The second polymer compound is introduced (2824) to themold at a gate 1902 and fill point 504, for each connected group ofupper and lower features. In one embodiment, there are 16 such gates andfill points on one tile. The second polymer flows by runners 502 to thethrough-hole(s) at step 2824. At step 2826, the second polymer flows ineach connected through-hole 602 from the lower surface to the uppersurface, reaching the cavity(ies) which each define respective upperfeature(s). The upper feature cavity(ies) are filled at step 2828. Atstep 2830, the crush ring(s) shut off the second polymer compound fromflashing across the upper surface of the part. The second polymercompound pushes any gas through vent hole(s) 2402, minimizing orobviating any defects in the upper feature(s). To positively assure thatthis is accomplished, at step 2832 second polymer compound may flowthrough each vent hole 2402 to protrude onto the lower surface 2306. Thecrush pad 2406 and associated mold half isolate this second polymerportion 2310 from next-adjacent lower features 800.

While the second polymer compound is molding the upper feature(s) atsteps 2824-2832, it can also create lower feature(s) at steps 2834-2840.At step 2834, second polymer compound flows from gate 1902 and fillpoint 504 into and through one or more runners 502. At step 2836, therunners 502 permit second polymer compound to reach each of the lowerfeature(s) 800, 802, where the cavity(ies) defining them are filled(2838). At step 2840, the crush pad(s) 2406, in conjunction with themating second-shot mold half (not shown), shut off the molten secondpolymer compound, preventing the flash of same over the lower surface2306. The mold half and crush pad(s) 2406 also isolate second polymerportion 2310 from the second polymer compound flowing in to formfeature(s) 800, 802. In this way, there is no hydraulic interferencebetween the molten polymer compound flowing into and forming the upperfeature(s) and the molten polymer compound flowing into and forming thelower feature(s), and any air or inert gas will be expelled from theupper surface features.

While embodiments of the present invention have been described in theabove detailed description and illustrated in the appended drawings, thepresent invention is not limited thereto but only by the scope andspirit of the appended claims.

We claim:
 1. A method for forming a modular floor tile for use increating a flooring surface comprising a plurality of such tiles, themethod comprising the steps of: molding a body of the tile from a first,relatively rigid thermoplastic polymer to have a lower surface and aplurality of spaced-apart groups of support member cores, the coreshaving bottom surfaces positioned to be disposed below the lower surfaceand each support member core having at least one sidewall disposed belowthe lower surface to extend to the bottom surface of the core; andovermolding, onto the cores, a skin from a second, relatively nonrigidthermoplastic polymer, the skin molded to adhere to the bottom surfaceof the core and to at least a portion of said at least one sidewall, theskin and the cores comprising the support members.
 2. The method ofclaim 1, and further comprising the steps of forming, laterally aroundeach of the support members, a smooth crush pad to be displaceddownwardly from the general lower surface of the body; and during saidstep of overmolding, using the crush pad to shut off the second polymerto thereby prevent flashing of the second polymer.
 3. The method ofclaim 1, and further comprising the steps of forming, in a mold, aplurality of runners which join a common fill point disposed adjacentthe general lower surface of the body to each of the support membercores; and during said step of overmolding, flowing the second polymercompound from the common fill point through the runners to each of thesupport member cores.
 4. The method of claim 3, and further comprisingthe steps of forming a second polymer compound gate to extend from anupper surface of the body to a lower surface thereof to communicate tothe runners; and injecting the second polymer compound into the gate onthe upper surface to mold the skin.
 5. The method of claim 3, andfurther comprising the steps of forming the body of the tile to have aplurality of through-holes each communicating a lower surface of thebody to an upper surface thereof; communicating said common fill pointto each of the through-holes; and during said step of overmolding,flowing the second polymer compound from the common fill point to eachof the through-holes and onto the upper surface of the body, to create aplurality of pads on the upper surface of the body.
 6. The method ofclaim 3, wherein the upper surface of the body includes a general uppersurface, the method further comprising the steps of forming, on theupper surface of the body, a plurality of smooth crush rings eachlaterally surrounding an area in which a pad is to be created and eachraised above the general upper surface of the body; and during said stepof overmolding, using the crush rings to shut off the second polymercompound, thereby preventing flashing of the second polymer compound. 7.The method of claim 3, and further comprising the steps of positioningthe through-holes to be adjacent to ones of the crush member cores; andduring said step of overmolding, flowing the second polymer compoundfrom the common fill point through the runners to the support membercores and to the through-holes.
 8. The method of claim 1, and furthercomprising the steps of providing, for each of a plurality of groups ofsupport members, a common fill point; and during said step ofovermolding, using the common fill points to introduce the secondpolymer compound to respective groups of the support members.